Spatial and Conceptual navigation in Early Blind people: Testing the scaffolding hypothesis of cognitive maps

Interaction with the environment is a crucial feature that characterizes intelligent biological systems. To do so the information acquired by the surroundings needs to be organized in flexible and generalizable structure, namely cognitive maps, which encode relational information, store it, and make it easily accessible and reusable. The hippocampal-entorhinal system plays a crucial role in the creation of cognitive maps, and, particularly, grid cells have been targeted as the main neural correlate. In humans, grid-like activity has been associated with the encoding of both spatial and abstract knowledge. However, in the field of cognitive maps, the precise relationship between spatial and conceptual knowledge remains unclear. Here, we take blindness as a model to test whether the mechanisms ontogenetically evolved to navigate in space scaffold the navigation through concepts or, on the contrary, if spatial and abstract knowledge develop independently. In this thesis, I provide, for the first time, evidence in favor of the scaffolding hypothesis by observing a reduction of the grid-like coding in the early blind individuals’ entorhinal cortex both during a spatial and a conceptual navigation task. Crucially, lack of visual experience seems to influence specifically the grid system, as, instead, the typical cortical networks that support spatial and conceptual navigation show a high resiliency to early visual deprivation. These findings will deepen significantly our understanding of the relationship between spatial and nonspatial concepts, opening the path to novel questions related to the development of the grid system and, more in general of the cognitive maps.